It's great to have the feedback on your own work, and you can learn from other people's mistakes almost more easily than you're own (they're so much easier to see!). But the benefits to being in a group don't end there. We all bring food, we eat, we critique, then we eat some more and (if there's more than one thing on the agenda) critique some more. We celebrate birthdays (none this month) and toast story sales and other victories. We support each other.
And let's face it, writing is very introverted—just you and the keyboard. It's nice to have some human interaction, especially from folks who have all been there.
Oddly enough, the group is called the Writer's Group From Hell (WGFH). My friend Risa, who has been in the group even longer than I have, says that in the past the name was more accurate. But we like it. Another friend said people have seen the acronym and assumed that WHFG was a radio station! All spec fic, all the time?